The business case for increased employer investment in health promotion and disease prevention programs remains tenuous. To support increased private sector investment in health promotion, this project will team a public health agency, the New York City Department of Health and Mental Hygiene (NYC DOHMH), with approximately 10 New York City employers, Cornell University researchers, analysts from Medstat, and the Wellness Council of America (WELCOA) to design, implement, and evaluate a comprehensive set of evidence-based worksite health promotion interventions. We will employ a quasi-experimental research design wherein employees at five worksites will be randomly assigned to a high-intensity (treatment) condition and employees at another five worksites (matched based on industry and other important characeristics) will be randomly assigned into a low-intensity (control) condition. The intervention period will last two years. The aim of the project is to determine the most effective methods that the Wellness at Work Division of the NYC DOHMH can apply to support area employers in their health promotion efforts. The demonstration will test the incremental effects of the high-intensity interventions developed and implemented by the NYC DOHMH, above and beyond interventions already being provided by New York City employers. The impacts of the NYC DOHMH programs will be assessed in terms of improvements in health behaviors, biometric measures, and health risk factors of employees; reductions in self-reported health care utilization and associated medical expenditures; improvements in employee productivity measured in terms of self-reported absenteeism and on-the-job presenteeism; and improvement in key organizational cost measures, employee attitudes toward work, satisfaction with the work environment, and improvement in overall wellbeing. A return-on-investment [ROI]) for this publicly supported health promotion intervention will also be determined.